Process for decolorizing hydrocarbon distillates



Dec. 5, 1933.

S. E. CAMPBELL PROCESS FOR DECOLORIZING HYDROCARBON DISTILLATES FiledApril 24, 1929 J&

Tan/r fig? (s a $2 2?" c r t r c r s a/My 44a 60a 4446 9a 65 INVENTORJamie/E far/pk Arm/m5 y Patented Dec. 5, 1933 erur PBGCESS F03DECGLGRKZING HYDRO- CARBGN DHSTILLATES 5 Claims.

This invention relates to a process for decolorizing oils andparticularly applicable to distillates derived from crude oils, such aspetroleum, shale oil, and the like, in the refining thereof.

The principal object of th invention is to provide a process fordecolorizi g distillates, which distillates will remain stabilized as tocolor after being subjected to the process.

A further object is to provide a process in which a minimum quantity oiacid is made available to decolorize a maximum quantity of distillate.

A further object is to provide process by which certain color formingcompounds and other i1npurities are continuously removed fromdistillates in such form that they may be recovered as byproducts ofvalue.

A further object is to provide a process by which gasoline, keroseneand/or other distillates are decolorized by the use of acid which iscontinucusly used until substantially exhausted in chemical reactionswith the distillates and/ or impurities therein.

In my co-pending application Serial No. 349,606, filed Mar. 25, 1929,there is disclosed a process in which distiilates are decolorizcd andthereby stabilized as to color by the use of dilute acid, or a diluteacid solution, containing, for instance, less than 93.19% H2804, or lessthan concentrated sulphuric acid of 66 B. gravity.

The use of dilute acid, through which the distillate is passed, providesfor the absorption by chemical reaction of color forming compoundscontained in the distillates, such as nitrogenous and other bases, andprovides that by the absorption of such bases in the dilute acid up tosubstantial exhaustion of the acid, the bases may be recovered in theform of by-products of value.

By reference to the drawing, which diagrammatically illustrates a howsheet of the process, a raw distillate, such as the gasoline fraction ofcrude petroleum, is supplied through a feed pipe 10 and valve 26 to atower 11, comprising the first of a plurality of dilute acid towers 11,11" and 11".

The plurality of towers 11, 11', 11", and 11 are connected in seriesthrough valve 27, pipe 14, valve 28, tower 11', valve 27, pipe 14',valve 28', tower 11", valve 27, pipe is", valve 28, tower 11", and valve27" to discharge the acid treated gasoline in a continuous stream flowinto pipe 15 initially.

The construction and function of each of the towers are alike andtherefore a dsecription of tower 11 will apply to all.

Tower 11 is filled with acid resistant inert ma terial 12, adapted toprovide large surface for corn tacting the distillate with the acid, andeach tower is filled partially, to the line X-X, with a dilute acidsolution through pipe 13 and valves 37, 37, 3'7 and 37", which acidsolution is initially supplied i'rom an exterior source through a valve13.

The acid solution may be any dilute acid solutlon, but preferably adilute sulphuric acid solution is used one, for instance, less than93.19% H2894, or about 50% H2804. The strength of the dilute acidsolution, however, will vary with the nature or the hydrocarbondistillate under treatment to obtain the desired results.

Pipe 15 divided at a valve 34 to direct the distillate on one side to a.valve 33 and a by-pass manifold connected to towers 11, 11, 11" and 11through valves 30, 30, 30", and 30 respectivezy, and on the other sideof valve 34 is a. withdrawal by-pass manifold 35 which connects the pipe15 with extensions of pipes 14, 14 and 14" through valves 31, 31' and31" respectively.

The object of the by-passing of the stream flow or distillate aroundvalve 34 is to be able to subject the distillate to acid treatment inthe plurality of towers in rotation so that the acid in each tower issubstantially exhausted, as will be further described.

A manifold 38 is connected to each tower 11, 11, 11 and 11" throughvalves 29, 29, 29" and 29" respectively for passing exhausted acid andreaction products to a storage tank 39 for further treatments.

By continuously flowing a stream of distillate from pipe 10 through theacid towers andconnections, as described, to pipe 15, (valves 26, 26",26", 29, 29', 29", 29", 30, 30, 30", 30', 37, 37', 3'7, 37", 31, 31',31" and 33 being closed) the distillate is contacted with successiveportions of a dilute acid solution in series relation, to the end thatthe color forming compounds comprising nitrogenous bases, and/or otherbasic impurities, in the distillate are absorbed in decreasing amountsin each tower in proportion as the stream is denuded of such compounds.

The denudation of the basic impurities in the distillate stream by suchflow in series causes the dilute acid solution in tower 11 to becomesubstantially exhausted by reaction with such impurities first, while inthe last tower 11" the acid 105 solution will be substantially fresh,the amount and strength of acid in each tower being regulated to thisend.

Upon the substantially complete exhaustion of the acid in tower 11,valves 26, 2'7, and 28 are 110 closed and valve 26' is opened tomaintain the stream flow through the remaining towers 11, 11'' and 11serially.

Valve 29 is now opened to withdraw the exhausted acid and reactionproducts through pipe 38 to tank 39, whereupon valve 29 is closed andvalve 37 opened to refill tower 11 with fresh weak acid solution.

Valves 37 and 34 are then closed and valves 33, 30, 27 and 31 opened,whereby tower 11 becomes the last in the series and tower 11 the firstin the series.

In this manner the plurality of towers are used in rotation to alwaysprovide that the stream of distillate shall be subject first to apartially spent acid solution, and last to a substantially fresh acidsolution, whereby substantially all color forming and other basicimpurities are removed by such treatment.

Not only does such treatment with a dilute acid solution insure theremoval of the desired impurities, but such is in strong contrast toknown treatments of distillates for the removal of such impurities bythe use of concentrated acid, in which there may be as much as of theoriginal strong acid drawn off in the acid sludge with the impuritiesand which is generally a total loss.

The dilute acid is substantially completely used up and the reactionproducts are in a form from which by-products of value may be recovered.

The stream of distillate thus treated with dilute acid solution isconveyed through pipe 15 to a settling tank 16, from which any acidcarried over is removed through a pipe 17, the rate of throughput beingso regulated that a minimum quantity of dilute acid is thus carriedover.

From tank 16 the distillate passes through a pipe 18 and valve 40 to analkali tower 19 which has previously been partially filled by the lineY-Y with a relatively strong alkaline solution, for example, a solutionof caustic soda, valves 43 and 49 being closed.

Such solution may be, for instance, a solution containing 30% of sodiumhydroxide, or other equivalent alkali, which absorbs the acidicimpurities in the acid treated distillate with avidity, to the end thatthe solution absorbs about an equal volume of acidic impurities, ormore, 'depending on the nature of the hydrocarbon material beingtreated, before becoming exhausted.

Weaker solutions may be used, as well as solutions of potassiumhydroxide, or sodium plumbite, but a strong alkaline solution isadvantageous to confine the alkaline treatment to a single passagethrough the alkaline solution, whereby the maximum amount of acidicimpurities may be concentrated therein in comparatively small volume andless frequent renewal of the alkaline solution will be required.

However, for convenience, two or more towers 19 and 19' are provided inseries, primarily to maintain continuous operation and secondly if it isdesired to use dilute alkali solutions. In the latter case, a pluralityof alkali towers may be arranged in series relation to be used inrotation as already described for the dilute acid towers.

Tower 19 may thus be connected through pipe 21 and valves 41 and 40 totower 19', likewise partly filled with caustic soda solution, thedistillate passing thence through pipe 42 and valve 41' to a settlingtank 22, from which any caustic soda carried over may be withdrawnthrough a pipe 43.

Thus, in operation, the acid treated distillate is passed through aplurality oi towers contain ing relatively strong caustic sodasolutions, in the first of which substantially all impurities of an acidnature are absorbed and the neutralization of any free acid is effected,the second tower, in the use of strong alkali, merely assuring that noacidic compounds remain in the distillate.

The passage of distillate through tower 19 continues until the causticsoda therein becomes substantially completely exhausted by reaction withacidic impurities, which include such compounds as phenols, cresols, andthe like, and/or naphthenic acids and the like whereupon the stream flowof distillates is continued by closing valves 40 and 41 and openingvalve 43.

The caustic solution in tower 19 being substantially fresh, insures thecontinuous removal of acidic impurities as previously described fortower 19.

Valve 44 is now opened and the exhausted caustic solution and reactionproducts are removed therethrough to line 45 and storage tank 46, whencethey may be withdrawn through pipe 47 and the acidic impuritiesrecovered as byproducts of value in many ways.

Valve 44 is now closed and valve 48 opened to partly refill tower 19with fresh caustic solution through a supply pipe 20 to be ready for useupon exhaustion of the caustic solution in tower 19, at which timevalves 43, 40, and 41 are closed and valves 49, 41, and a valve 49 in aby-pass line 50 are opened, to permit the recharging of tower 19' withfresh alkali solution.

By the steps of the process thus described, the selective treatment of astream of distillate is provided to first remove basic impurities, andthen remove acidic impurities, in a continuous manner in which the acidand alkali used are The nitrogenous bases and other basic 1m puritiesremoved by the dilute acid treatment and collected in tank 39 may berecovered by a treatment such as is described in United States PatentNo. 1,636,136, the strength of the dilute acid solutions employed beingsuch as to convert the basic compounds into sulphates without materialpolymerization, or without reacting materially on acidic impurities tochange, or possibly destroy, such as are desired to be collected in thealkali treatment for recovery as products of value.

Such change, or destruction, may be accomplished by the use ofconcentrated acid in towers 11, 11', 11 and 11" when treating adistillate such as gasoline.

The distillate, after acid and alkali treatmerits, in settling tank 22may still contain cerof dilute acid towers ll, 11, 11'', and 11", t0

be used in rotation whereby the distillate is first contacted withpartially spent concentrated acid and lastly with substantially freshconcentrated acid, to the end that all the concentrated acid issubstantially saturated with impurities, or exhausted.

The concentrated acid preferably used is a strong sulphuric acid in theneighborhood of 66 B. gravity and, inasmuch as the mode of operation ofthe strong acid towers is like that already described for the weak acidtowers, a description of such involves needless repetition to oneskilled in the art.

However, the function of the concentrated acid treatment and the resultsachieved thereby comprise an important step in my process.

While concentrated acid decolorizes a distillate to the required color,in ordinary acid and alkali treatments of distillate, it is known thatup to 80% of the concentrated acid is withdrawn in the acid sludge withthe reaction products and is only recoverable with difficulty.

Likewise, on treating a distillate primarily with concentrated acid, theoxidizing and other chemical effects thereof may change the basicimpurities into compounds which are too complex to recover inappreciable quantities, inasmuch as such compounds are in a form notsusceptible of easy recovery.

Presumably, also, certain of the hydrocarbon compounds are oxidized byconcentrated acid treatment, forming complex reaction mixtures, and arewithdrawn in the body of the exhausted concentrated acid.

The further objects of my invention by the succeeding enumerated stepsinclude the recovery of hydrocarbons oxidized by concentrated acid in aplurality of treatments whereby the concentrated acid is substantiallyexhausted, the elimination of substantially all concentrated acidlosses, the use of a dilute acid recovered from the concentrated acidtreatment, and the final decolorization of the distillate treated to acolor of 30+ on the Saybolt colorimeter and the stabilization of thecolor of the distillate.

To these ends the partially decolorized distillate is passed by pipes 51and 10a through the towers 11a, 11b, 11c, and 11d, wherein it issubjected to the action of concentrated acid, whereby it is finallycleared of the remaining chromogenic substances to gain its color andbrilliancy and whereby certain hydrocarbon sulphates are formed by thechemical action of the concentrated acid.

Upon exhaustion of the concentrated acid in any of the towers 11a, 11b,11c, and 11d, the reaction products are withdrawn through line 38a to astorage tank 39a. The treated distillate passes through pipe 15a to asettling tank 16a or to other suitable means of separating acid anddistillate, whence any concentrated acid carried over is withdrawnthrough a pipe 171:.

From settling tank 16a the distillate passes through a pipe 18a toneutralizing tanks 19a and 191) containing a suitable alkaline solutionof sufiioient strength to take care of any acidity in the distillate andthence through a pipe 42a to a wash tank 56 to which water is suppliedthrough a line 57, whereby any alkali is removed and withdrawn throughpipe 58.

The distillate thus purified, decolorized, and brilliant, after removalof water, passes from wash tank 56 through line 59 to storage or otheruses.

The exhausted alkali may be withdrawn from either of the towers 19a, or19b through a line 45a to a storage tank 4641, from which tank it may betaken through a pipe 47a for any desired purpose.

The exhausted concentrated acid, together with reaction productsthereof, in the tank 39a is fed in predetermined quantities through aline 60 to a chamber 61 filled with water from pipe 5'7 and valve 62 toa predetermined level.

Chamber 61 generally may be of a well known type containing agitatingmechanism and having the temperature of its contents controlled by aseries of coils 63 through which a refrigerating medium is passed. Coils63 may be located externally, or internally, of chamber 61, or both.

The temperature of the mixture in chamber 61 is thus controlled to bemaintained at any desired degree. In the present case a temperature ofabout 33 F. is sufficient, with agitation, to hydrolyze the reactionproducts resulting from the concentrated acid treatment, to the end thatcertain compounds of value are formed.

Alcoholic, or other derivatives of hydrolysis may be withdrawn fromchamber 61 through valve 64 while the acid released is in such form andstrength as to be available for use in the weak acid towers 11, 11',11", and 1", and such is therefore passed, as required, through a valve65 and pipe 66 to the weak acid charging line 13.

In this manner the further treatment of the distillate by concentratedacid not only completes the decolorization, with stabilization, of thedistillate, but by the further action of hydrolysis of the spent acid,by-products of value are recovered, together with weak acid for reuse inthe initial step.

While these novel results are obtained, it must not be overlooked thatthe waste of concentrated acid, as normally used, is substantiallyeliminated.

The process as described is particularly adaptable to a distillate suchas the straight run gasoline obtained from a California crude oil.However, I do not limit myself to treating such fractions, as kerosenesand the gasoline fractions from cracked oils may likewise be treated toadvantage, the main difference being in the strength of acid used.

Or the treatment of different fractions may be undertaken. For instance,the gasoline fraction from a straight run crude oil may be passed intothe dilute acid system through pipe 10 and after passing through thetreatment as described, may be withdrawn through a line 53 to a filter6''! containing an adsorbent earth, such as fullers earth, and thencethrough a pipe 54 to storage or use.

The action of the fullers earth is to remove certain chromogeniccompounds unaffected by the dilute acid or alkali treatment, which causeturbidity, and to thereby impart the desired brilliancy to the finishedproduct, decolorized and stabilized in color.

At the same time a kerosene fraction may be run into the concentratedacid towers through valve 55 and line 10a, wherein it is brought to thedesired color.

Such combination of treatments is often desired, because kerosenerequires as a rule stronger or a greater quantity of acid for effectivetreatment than gasoline, but, by processes heretofore known, the wasteof concentrated acid in the acid sludge is very high and this waste I amnow enabled to materially reduce and at the same time use the recovereddilute acid in a concurrent step treating gasoline.

The process is equally effective for fractions obtained from crackedoils, in which case it is desirable to apply cooling apparatus to theacid towers to control the exothermic heat of reaction, there being thisdifference between the fractions from straight run crude oil and fromcracked oils, that there is but slight rise in temperature when treatingthe fractions from straight run crude oils.

I claim as my invention:

1. A process for decolorizing distillates which comprises: passing astream of hydrocarbon distillate through a dilute sulphuric acidsolution in the presence of contact material and an alkaline solution insuccession then through a plurality of chambers containing contactmaterial and concentrated sulphuric acid and arranged in seriesrelation, continuing the passage of distillate until the concentratedsulphuric acid is substantially exhausted in the chambers in rotation,removing the exhausted concentrated sulphuric acid and reaction productsfrom successive chambers, and finally treating the exhaustedconcentrated sulphuric acid and reaction products with water to obtainsaid dilute sulphuric acid solution.

2. A process for decolorizing distillates which comprises: passing astream of hydrocarbon distillate through a dilute sulphuric acidsolution in the presence of contact material and an alkaline solution insuccession then through a plurality of chambers containing contactmaterial and concentrated sulphuric acid and arranged in seriesrelation, continuing the passage of distillate until the concentratedsulphuric acid is substantially exhausted in the chambers in rotation,removing the exhausted concentrated sulphuric acid and reaction productsfrom successive chambers, and finally treating the exhaustedconcentrated sulphuric acid and reaction products with Water at a lowtemperature to obtain said dilute sulphuric acid solution.

3. A process for decolorizing distillates which comprises: passing astream of hydrocarbon distillate through a dilute sulphuric acidsolution in the presence of contact material and an alkaline solution insuccession then through a plurality of chambers containing contactmaterial and concentrated sulphuric acid and arranged in seriesrelation, continuing the passage of distillate until the concentratedsulphuric acid is substantially exhausted in the chambers in rotation,removing the exhausted concentrated sulphuric acid and reaction productsfrom successive chambers, and finally treating the exhaustedconcentrated sulphuric acid and reaction products with water at about 33F. to obtain said dilute sulphuric acid solution.

4. A process for decolorizing distillates which comprises: passing astream of hydrocarbon distillate through a dilute sulphuric acidsolution in the presence of contact material and an alkaline solution insuccession then through a plurality of chambers containing contactmaterial and concentrated sulphuric acid and arranged in seriesrelation, continuing the passage of distillate until the concentratedsulphuric acid is substantially exhausted in the chambers in rotation,removing the exhausted concentrated sulphuric acid and reaction productsfrom successive chambers, and finally treating the exhaustedconcentrated sulphuric acid and reaction products to obtain said dilutesulphuric acid solution and alcoholic derivatives of the distillate.

5. A process for decolorizing distillates which comprises: passing astream of hydrocarbon distillate through a dilute sulphuric acidsolution in the presence of contact material and an alkaline solution insuccession, then through a plurality of chambers containing contactmaterial and concentrated sulphuric acid and arranged in seriesrelation, continuing the passage of distillate until the concentratedsulphuric acid is substantially exhausted in the chambers in rotation,removing the exhausted concentrated sulphuric acid and reaction productsfrom successive chambers, and finally treating the exhaustedconcentrated sulphuric acid and reaction products to obtain said dilutesulphuric acid solution.

SUMNER E. CAMPBELL.

